Damaged Propeller Blades

This report covers case histories of failures in fixed-wing light airplane and helicopter components. In a 2025-T6 or 2219 aluminum alloy propeller blade that failed near the tip, cracks started on the leading edge at surface damage in the critical area-the zone between 4 and 10 in. from the tip of the blade. Incorrect dressing and inadequate pre-flight inspection were the two main causes. Two other types of propeller blade fatigue failures resulted mainly from propeller straightening operations, usually performed after previous blade bending damage. To eliminate blade tip failures, all surface-damaged material should be removed and polished smooth before further flight. The blade should be correctly dressed. Also, the tachometer should be calibrated to ensure the engine/propeller combination is not operated in the critical speed range at normal cruising speeds.